• 제목/요약/키워드: film density

검색결과 2,373건 처리시간 0.03초

고집적 DRAM소자용 14/50/50 PLZT 박막의 특성에 관한 연구 (A Study on Characteristic of the 14/50/50 PLZT Thin Film for DRAM Capacitor)

  • 박용범;장낙원;백동수;마석범;최형욱;박창엽
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 1999년도 춘계학술대회 논문집
    • /
    • pp.118-121
    • /
    • 1999
  • PLZT thin films were fabricated with different energy density by pulsed laser deposition. PLZT films deposited on Pt/Ti/SiO$_2$/Sr substrate. This PLZT thin films of 5000$\AA$ thickness were crystallized at $600^{\circ}C$, 200mTorr $O_2$ pressure for 2 J/$\textrm{cm}^2$ laser energy density. 14/50/50 PLZT thin film showed a maximum dielectric constant value of $\varepsilon$$_{r}$=1289.9 P-E hysteresis loop of 14/ 50/50 PLZT thin film was slim ferroelectric. Leakage current density of 14/50/50 PLZT thin film was 10/ sup -7/=A/$\textrm{cm}^2$.>.

  • PDF

Al6061합금의 PEO 피막 형성에 미치는 AC 전류밀도의 영향 (Effect of AC Current Density on the PEO Film Formation of Al6061 Alloy)

  • 박철기;문성모;정인모;윤대수
    • 한국표면공학회지
    • /
    • 제52권3호
    • /
    • pp.138-144
    • /
    • 2019
  • In this work, PEO (Plasma Electrolytic Oxidation) film formation behavior of Al6061 alloy was investigated as a function of applied current density of AC at 310 Hz in the range from $120mA/cm^2$ to $300mA/cm^2$ in 0.5 M $Na_2SiO_3$ solution. When applied current density is lower than a critical voltage of about $132mA/cm^2$, voltage reaches a steady-state values less than 120 V without generation of arcs and metallic color of the alloy surface remains. On the other hand, when applied current density exceeds about $132mA/cm^2$, voltage increases continuously with time and arcs are generated at more than 175 V, resulting in the formation of PEO films with grey colors. Two different types of arcs, large size and small number of arcs with orange color, and small size and large number of arcs with white color, were generated at the same time when the PEO film thickness exceeds about $50{\mu}m$, irrespective of applied current density. Formation efficiency of the PEO films was found to increase with increasing applied current density and the growth rate was obtained to be about $5{\mu}m/min$ at $300mA/cm^2$. It was also found that surface roughness of the PEO films with $70{\mu}m$ thickness is not dependent on the applied current density.

파노라마방사선사진에서 골형태 계측과 구내표준필름에서 구리당량치의 상관관계 (The correlationship between mandibular radiomorphometric indices in panorama and bone mineral density in Cu-equivalent image of intraoral film)

  • 김재덕
    • Imaging Science in Dentistry
    • /
    • 제33권3호
    • /
    • pp.131-135
    • /
    • 2003
  • Purpose: To determine whether the mandibular radiomorphometric indices in panoramic radiography are correlated with the bone mineral density of Cu-equivalent images in intraoral film. Materials and Methods: The bone mineral density (BMD) of the mandibular premolar area was measured in the Cu-equivalent image of intraoral film. The Panoramic Mandibular Index (PMI) and Mandibular Cortical Width (MCW) were measured in panoramic radiographs of six dry mandibles, and the Pearson correlation between PMI, MCW, and BMD were tested. Results: There were no significant correlations between PMI and BMD (r = 0.280), nor between MCW and BMD (r =0.237). Conclusion: The results show that PMI and MCW were poor diagnostic indicators of mandibular BMD in the six dry mandibles used in this study. The correlationship between the mandibular radiomorphometric indices (PMI and MCW) and mandibular BMD needs to be researched further using large in vivo patient samples.

  • PDF

Patterned free-standing diamond field emitters for iarge area field emission display applications

  • Kim, Sung-Hoon
    • Journal of Korean Vacuum Science & Technology
    • /
    • 제3권1호
    • /
    • pp.10-15
    • /
    • 1999
  • Using micro-wells on the Mo substrate, we could obtain various tubular-volcano-types of free-standing diamond field emitters by depositing a diamond film detaching the film and turning the film upside down. The field emission characteristics of these structures were investigated as a function of size, shape and the number density of the tubular-volcano-type diamond field emitters. The field emission characteristics, especially the current density, were greatly enhanced with increasing the number density of the tubular-volcano-type diamond field emitters on the Mo substrate. Based on these results, we suggest that the reduction of the well size can give better field emission characteristics by the increase in the number density of the tubular-volcano-type diamond field emitters. Finally, we suggest the feasibility of fabricating a large-area field emission display using our patterned tubular-volcano-type free-standing diamond field emitters.

  • PDF

수소연료를 이용하는 원자층증착 박막전해질 세라믹연료전지의 초기성능 저하에 관한 연구 (A Study on the Initial Performance Degradation of Hydrogen-Fueled Ceramic Fuel Cell with Atomic Layer-Deposited Thin-Film Electrolyte)

  • 지상훈
    • 한국수소및신에너지학회논문집
    • /
    • 제32권5호
    • /
    • pp.410-416
    • /
    • 2021
  • The initial electrochemical performance of ceramic fuel cell with thin-film electrolyte was evaluated in terms of peak power density ratio, open circuit voltage ratio, and activation/ohmic resistance ratios at 500℃. Hydrogen and air were used as anode fuel and cathode fuel, respectively. The peak power density ratio reduced as ~17% for 40 minutes, which rapidly decreased in the early stage of the performance evaluation but gradually decreased. The open circuit voltage ratio decreased with respect time; however, its time behavior was remarkably different with the reduction behavior of the peak power density ratio. The activation resistance ratio increased as ~15% for 40 minutes, which was almost similar with the time behavior of the peak power density ratio.

Enhancement of the nucleation density for diamond film on the pretreated glass substrate by the application of cyclic modulation of the source-gas flow rate

  • Kim, T.-G.;Kim, S.-H.;Kim, Y.-H.
    • Journal of Korean Vacuum Science & Technology
    • /
    • 제4권1호
    • /
    • pp.18-22
    • /
    • 2000
  • For the enhancement of the nucleation density of the diamond film, we introduced the cyclic process. The cyclic process was carried out by the on/off control of CH$_4$ flow rate for a relatively short time (10 min), compared with the total reaction time (6 h). Prior to depositing the diamond film, we made the pretreated glass substrate via the unidirectional scratch using ∼l $\mu\textrm{m}$ size diamond powders. Diamond films were deposited on the pretreated glass substrate in a microwave plasma enhanced chemical vapor deposition (MPECVD) system. We observed the enhancement of the nucleation density of the diamond films caused by the cyclic process. Detailed surface morphologies of the substrate were investigated after the cyclic process. Based on these results, we discussed the cause for the enhancement of the nucleation density on the pretreated glass substrate by the cyclic process.

  • PDF

Structural, Optical and Photoconductive Properties of Chemically Deposited Nanocrystalline CdS Thin Films

  • Park, Wug-Dong
    • Transactions on Electrical and Electronic Materials
    • /
    • 제12권4호
    • /
    • pp.164-168
    • /
    • 2011
  • Nanocrystalline cadmium sulphide (CdS) thin films were prepared using chemical bath deposition (CBD), and the structural, optical and photoconductive properties were investigated. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size, dislocation density and lattice constant of CBD CdS thin films were investigated. The dislocation density of CdS thin films initially decreases with increasing film thickness, and it is nearly constant over the thickness of 2,500 ${\AA}$. The dislocation density decreases with increasing the crystallite size. The Urbach energies of CdS thin films are obtained by fitting the optical absorption coefficient. The optical band gap of CdS thin films increases and finally saturates with increasing the lattice constant. The Urbach energy and optical band gap of the 2,900 A-thick CdS thin film prepared for 60 minutes are 0.24 eV and 2.83 eV, respectively. The activation energies of the 2,900 ${\AA}$-thick CdS thin film at low and high temperature regions were 14 meV and 31 meV, respectively. It is considered that these activation energies correspond to donor levels associated with shallow traps or surface states of CdS thin film. Also, the value of ${\gamma}$ was obtained from the light transfer characteristic of CdS thin film. The value of ${\gamma}$ for the 2,900 A-thick CdS thin film was 1 at 10 V, and it saturates with increasing the applied voltage.

전기화학 Carbon Film 합성 (Fabrication of Carbon Thin Film by Electrochemical Method)

  • 이상헌
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
    • /
    • pp.128-129
    • /
    • 2007
  • Electrochemical method of carbon film on silicon substrate in methanol solution was carried out with various current density, solution temperature and electrode spacing between anode and cathode. The carbon films with smooth surface morphology and high electrical resistance were formed when the distance between electrode was relatively wider. The electrical resistance of the carbon films were independent of both current density and solution temperature.

  • PDF

구리당량 영상작성에 의한 골밀도계측방법의 평가 (Assessment of the Measurement Method of the Bone Mineral Density on Cu-Equivalent Image)

  • 김재덕
    • Imaging Science in Dentistry
    • /
    • 제30권2호
    • /
    • pp.101-108
    • /
    • 2000
  • Purpose : The effects of step numbers of copper wedge and exposure on the coefficient of determination (r²) of the conversion equation to Cu-equivalent image and on the Cu-equivalent value (mmCu) and it's coefficient of variation measured at each copper step and the mandibular premolar area were evaluated. Method: Digital image analyzing system consisted of scanner, personal computer, and a stepwedge with 10 steps of 0.03 mm copper in thickness as reference material was prepared for quantitative assessment of the bone mineral density. NIH image program was used for analyzing images. Results : The film having moderately high film density showed the discrepancy between the real thickness and the measured Cu-equivalent value of each copper step. The Cu-equivalent image was dependent on the determinational coefficient of the conversion equation than the coefficient of variance of the measured value. Conclusion : Obtaining conversion equation with high coefficient of determination and proper film exposure are supposed to be neccessary for quantitative assessment of bone density. Multiple steps in the range of the corresponding copper thickness to the bone density of the area to be measured should be prepared.

  • PDF

PLD법에 의한 고집적 DRAM용 PLZT 박막의 레이저 에너지 밀도에 따른 특성 (Laser Energy Density Dependence Characteristics of PLZT Thin Films prepared by a PLD for Memory Device)

  • 마석범;장낙원;백동수;최형욱;박창엽
    • 한국전기전자재료학회논문지
    • /
    • 제13권1호
    • /
    • pp.60-65
    • /
    • 2000
  • The structural and electrical characteristics of PLZT thin films fabricated onto Pt/Ti/SiO\ulcorner/Si substrates by a pulsed laser deposition were investigated to develop the high dielectric thin films were fabricated with different energy density by pulsed laser deposition. This PLZT thin films of 5000 thickness were crystallized at 600 $^{\circ}C$, 200 mTorr O\ulcorner pressure for 2 J/$\textrm{cm}^2$ laser energy density, the arain structure was transformed from planar to columnar grain. It was clearly noted from the SEM observations that oxygen pressured laser powers affect microstructures of the PLZT thin films. 14/50/50 PLZT this film showed a maximum dielectric constant value of $\varepsilon$\ulcorner=1289.9. P-E hysteresis loop of 14/50/50 PLZT thin film was flim ferro-electric. Leakage current density of 14/50/50 PLZT thin film was 10\ulcorner A/$\textrm{cm}^2$.

  • PDF